feat(ga-agent): Add GA Agent project with decomposed architecture

Create workspace for building Google Analytics Claude Skill with:
- 5 independent components (MCP setup, skill, dimension explorer, Slack reporter, realtime watcher)
- Comprehensive project plan and documentation
- Step-by-step setup guides for each component

Components:
1. MCP Setup - GA4 + BigQuery MCP server installation
2. GA Agent Skill - Core Claude Skill for interactive analysis
3. Dimension Explorer - Validate dims/metrics with explanations
4. Slack Reporter - Automated reports to Slack (P2)
5. Realtime Watcher - Real-time monitoring (deferred)

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

ga-agent-project/01-mcp-setup/README.md

@@ -0,0 +1,143 @@
+# Component 1: MCP Setup
+
+**Type:** Infrastructure
+**Priority:** P0
+**Status:** Not Started
+
+## Goal
+
+Install and configure GA4 + BigQuery MCP servers for Claude Code.
+
+## Prerequisites
+
+- Google Cloud account
+- GA4 property access
+- `gcloud` CLI installed
+
+## Setup Steps
+
+### Step 1: Google Cloud Project
+
+```bash
+# Authenticate
+gcloud auth login
+
+# Set project (create if needed)
+gcloud config set project YOUR_PROJECT_ID
+
+# Enable APIs
+gcloud services enable \
+  analyticsdata.googleapis.com \
+  analyticsadmin.googleapis.com \
+  bigquery.googleapis.com
+```
+
+### Step 2: Service Account
+
+```bash
+# Create service account
+gcloud iam service-accounts create ga-mcp-agent \
+  --display-name="GA MCP Agent"
+
+# Get email
+SA_EMAIL="ga-mcp-agent@YOUR_PROJECT_ID.iam.gserviceaccount.com"
+
+# Grant BigQuery roles
+gcloud projects add-iam-policy-binding YOUR_PROJECT_ID \
+  --member="serviceAccount:$SA_EMAIL" \
+  --role="roles/bigquery.dataViewer"
+
+gcloud projects add-iam-policy-binding YOUR_PROJECT_ID \
+  --member="serviceAccount:$SA_EMAIL" \
+  --role="roles/bigquery.jobUser"
+
+# Download key
+gcloud iam service-accounts keys create \
+  ../config/service-account.json \
+  --iam-account=$SA_EMAIL
+```
+
+### Step 3: GA4 Property Access
+
+1. Go to [GA4 Admin](https://analytics.google.com/)
+2. Property → Property Access Management
+3. Add user: `ga-mcp-agent@YOUR_PROJECT_ID.iam.gserviceaccount.com`
+4. Role: Viewer
+
+### Step 4: Install GA4 MCP Server
+
+```bash
+# Clone official server
+git clone https://github.com/googleanalytics/google-analytics-mcp.git
+cd google-analytics-mcp
+
+# Setup Python environment
+python -m venv venv
+source venv/bin/activate
+pip install -e .
+
+# Test
+export GOOGLE_APPLICATION_CREDENTIALS="../config/service-account.json"
+python -m google_analytics_mcp --help
+```
+
+### Step 5: Install BigQuery MCP Server
+
+```bash
+# Test with npx (no install needed)
+npx -y @ergut/mcp-bigquery-server \
+  --project-id YOUR_PROJECT_ID \
+  --location us-central1 \
+  --key-file ../config/service-account.json
+```
+
+### Step 6: Configure Claude Code
+
+Add to `~/.claude/mcp_servers.json`:
+
+```json
+{
+  "mcpServers": {
+    "google-analytics": {
+      "command": "python",
+      "args": ["-m", "google_analytics_mcp"],
+      "cwd": "/path/to/google-analytics-mcp",
+      "env": {
+        "GOOGLE_APPLICATION_CREDENTIALS": "/path/to/service-account.json"
+      }
+    },
+    "bigquery": {
+      "command": "npx",
+      "args": [
+        "-y",
+        "@ergut/mcp-bigquery-server",
+        "--project-id", "YOUR_PROJECT_ID",
+        "--location", "us-central1",
+        "--key-file", "/path/to/service-account.json"
+      ]
+    }
+  }
+}
+```
+
+### Step 7: Verify
+
+```bash
+# Restart Claude Code, then:
+mcp-cli servers
+# Should show: google-analytics, bigquery
+
+mcp-cli tools google-analytics
+mcp-cli tools bigquery
+```
+
+## Checklist
+
+- [ ] GCP project configured
+- [ ] APIs enabled
+- [ ] Service account created
+- [ ] GA4 access granted
+- [ ] GA4 MCP installed
+- [ ] BigQuery MCP installed
+- [ ] Claude Code configured
+- [ ] Connection verified